The present invention discloses a scroll compressor wherein a complex economizer passage is easily milled into an end face of either the fixed scroll member or a covering valve plate.
Scroll compressors are becoming widely utilized in refrigerant compression applications. As known, a scroll compressor essentially comprises fixed and orbiting scrolls that have interfitting spiral wraps which define a plurality of compression passages. The orbiting scroll moves relative to the fixed scroll to entrap and close chambers of fluid which are then compressed towards a central discharge port in the fixed scroll.
One challenge with refrigerant compression applications is to increase the heat transfer capacity of the refrigeration cycle. One known technique for increasing heat transfer capacity is the use of an economizer circuit which includes entry ports in the compressor. Economizer entry ports communicate intermediate pressure fluid into a scroll compression chamber at a point just after the chamber is closed. By injecting additional fluid into the chamber, the economizer entry ports increase the volume of compressed fluid.
The design of the scroll compressor wraps is quite complex. The points in the cycle at which the two scroll compression wraps come together to enclose a chamber varies with the particular scroll design. Thus, there is a need to accurately position the economizer entry port at a desired optimum position.
In the prior art, the economizer entry ports have been communicated to suction fluid through passages that are drilled or machined across an intermediate plane within the fixed scroll. The economizer entry port is then drilled into the base of the fixed scroll to communicate with the crossing economizer passages.
With this prior art, the machining of the economizer passages into the fixed scroll has been quite time consuming and complex. Further, once an optimum position for the economizer entry ports has been selected, the shape of the crossing passage has sometimes been quite complex. It is very difficult to precisely control the exact desired shape of the economizer passages and achieve a complex passage.
In some applications it may be desirable to have economizer entry ports on both sides of the central axis of the fixed scroll. In the known art, this has proven difficult to achieve since the discharge port is typically directly in the center of the fixed scroll. Thus, the crossing economizer passages must somehow move around the central discharge port. With the cross-drilled passages through the fixed scroll, this has been somewhat difficult to achieve.